<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .h {
            font-size: 30px;
        }

        .h3 {
            font-weight: normal;
        }

        .blod {
            font-weight: 700;
        }

        .style {
            font-style: italic;
        }
    </style>
</head>

<body>
    <h3 class="h3 style">标题</h3>
    <div class="h blod">neirong</div>
</body>

</html>